This section is intended to introduce various aspects of the art, which may be associated with exemplary embodiments of the present disclosure. This discussion is believed to assist in providing a framework to facilitate a better understanding of particular aspects of the present invention. Accordingly, it should be understood that this section should be read in this light, and not necessarily as admissions of prior art.
Some approaches to lower CO2 emissions include fuel de-carbonization or post-combustion capture. However, both of these solutions are expensive and reduce power generation efficiency, resulting in lower power production, increased fuel demand and increased cost of electricity to meet domestic power demand. Another approach is an oxy-fuel gas turbine in a combined cycle. However, there are no commercially available gas turbines that can operate in such a cycle.
The original oxy-fuel concept is based on the combustion of hydrocarbons with pure oxygen, which results in extremely high temperatures. Such high temperatures lead to problems in combustor life and also the development of Polycyclic Aromatic Hydrocarbons (PAHs), which lead to soot production. Numerous solutions to these issues have been attempted with varying levels of success, including using carbon dioxide as a mass flow gas through the turbine instead of air. However, this approach and others require specialized turbine equipment that is not yet commercially available.
U.S. Pat. No. 5,724,805 discloses a power plant having a gas turbine fueled by hydrocarbons mixed with an oxygen/carbon dioxide mixture. However, the disclosure states that the O2/CO2 mixture has more O2 than air and therefore burns at very high temperatures requiring a large combustor chamber to allow time for the combustion gasses to gradually cool so less carbon monoxide (CO) is produced. As such, a specialized, non-standard combustor must be used for the techniques in the '805 reference to be practiced.
As such, there is still a substantial need for methods and systems to effectively control the temperature and composition of combustion product streams.